Battery Pack Temperature-Based Charging Current Control

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Solution Overview

Problem

Lithium ion battery charging systems face safety risks due to lithium metal deposition at low temperatures and overheating at high temperatures, requiring adaptive charging current management to prevent short-circuits and temperature extremes, while existing solutions either increase battery pack size or cause electromagnetic disturbances.

Innovation Solution

A battery pack with a dual charging circuit system that adjusts charging current based on temperature, using a constant current circuit at low temperatures to rapidly increase the battery temperature to a standard range and a switching current circuit at high temperatures to prevent overheating, without modifying the existing apparatus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a large charging current is applied at low temperature, then charging speed is improved, but lithium metal deposition occurs on the negative electrode

Engineering Contradiction:

Improvecharging speedVSAvoidlithium metal deposition

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the charging current parameter based on temperature conditions. At low temperatures (below 10°C), the charging current is limited to a first value to prevent lithium metal deposition. At standard temperatures (10°C or higher), the charging current is increased to a second value for faster charging. This dynamic parameter adjustment resolves the contradiction between charging speed and safety.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If a large charging current is applied at high temperature, then charging speed is improved, but battery cell temperature exceeds upper limit

Engineering Contradiction:

Improvecharging speedVSAvoidbattery cell temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The patent adjusts the charging current parameter based on temperature conditions. When the battery cell temperature is 45°C or higher, the charging current is limited to a third value to prevent overheating. This dynamic parameter adjustment resolves the contradiction between charging speed and temperature control.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If a switching control method is used to generate charging current, then charging efficiency is improved, but electromagnetic disturbance occurs

Engineering Contradiction:

Improvecharging efficiencyVSAvoidelectromagnetic disturbance

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses periodic switching control to generate charging current. The switching element is turned on and off periodically to control the charging current flow. This periodic action enables efficient charging while the control circuit manages the switching frequency to minimize electromagnetic disturbance.

Inventive Principle:

Principle #19Periodic action

4Reliability

If temperature-based charging current control is implemented, then safety is improved, but device complexity increases

Engineering Contradiction:

Improvecharging safetyVSAvoidcharging circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements temperature-based charging current control by changing the charging current parameter according to detected temperature conditions. The control circuit receives temperature information and adjusts the charging current to appropriate values (first, second, or third values) based on temperature ranges, improving safety without requiring complex additional hardware.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables safe and efficient charging by maintaining the charging current within safe limits, reducing the risk of lithium metal deposition and overheating, while allowing the use of a single setting current battery charger without adding modifications to the existing apparatus, thus ensuring safety and reducing charging time.

Implementation Method 1

a temperature detecting element configured to detect a temperature of the battery cell

Methodology Applied

Scientific EffectTemperature detection:

Implementation Method 2

a first charging circuit configured to generate a constant current from the charging current

Methodology Applied

Scientific EffectElectrochemical charging:

Implementation Method 3

a second charging circuit configured to generate a switching current from the charging current

Methodology Applied

Scientific EffectSwitching current control:

Data Source

PatentUS7948212B2Battery pack and charging method

Publication Date: 2011.05.24 LENOVO SWITZERLAND INTERNATIONAL GMBH

AI summary

In a battery pack with battery charger, a circuit derives a relatively low constant current from the charge current of the battery charger, and this relatively low constant current is used to charge the battery pack when temperature is below a threshold. Otherwise, the charge current from the battery charger is used, at least up to a high temperature threshold.